The present application will pursue the following objectives: (1) Prolongation of allograft survival after in vitro culture. a) To determine the optimal (least toxic to other cells) tissue culture conditions which will kill donor leukocytes (macrophages); b) To determine if these conditions will allow survival of thyroid and pancreatic tissues in tissue culture as evidenced by histological examination; c) To determine if these conditions will allow survival of thyroid and pancreatic tissues in tissue cultures as evidenced by functional tissue; d) To determine if the successful "optimal conditions" found in part 2 will permit successful allogeneic thyroid and pancreas transplantation first, in the mouse, and later in a larger animal, the Yucatan Miniature Pig. (2) The induction of arginase in macrophages. a) Purification of mouse liver and peritoneal cell arginase and production of antisera to these proteins; b) Determine the specific cell type in the peritoneal cell population producing the arginase and determine whether the increas in arginase represents increased synthesis, decreased secretion or an unmasking of an inactive precursor; c) Determine the source of calmodulin in serum; d) Determine if calmodulin levels are increased in tumor bearing animals and patients.